Suresh D. Kulkarni | Searcharxiv

arXiv2020

Second and third harmonic nonlinear optical process in spray pyrolysed Mg:ZnO thin films

In the present study, Mg-doped ZnO (MZO) nanofilms (NF) were grown by spray pyrolysis technique. X-ray diffraction (XRD) patterns have shown an intense peak oriented along (002) crystalline plane confirming crystalline origin of grown MZO films. Atomic force microscopy (AFM) data revealed that the average roughness decreased significantly upon Mg doping from 20.3 nm to 4.72 nm. Ambient temperature photoluminescence spectra accounted for four emission bands in the visible spectral region due to the presence of various intrinsic defect centres in the films. The non-linear absorption coefficient beta_eff were estimated by open aperture Z-scan technique and found to be in the order of 10-2 (cm/W) and indicates a positive absorption nonlinearity. Additionally, it was observed that incorporation of the metal Mg ions leads to a decay of the second harmonic generation (SHG) and to a non-regular increase of the third harmonic generation (THG).

cond-mat.mtrl-sci↗

arXiv2020

Laser stimulated second and third harmonic optical effects in F: SnO2 nanostructures grown via chemical synthetic route

Laser stimulated second and third harmonic generation effects in Fluorine doped tin oxide (F:SnO2) nanostructures versus the fluorine content is presented. The F:SnO2 nanostructures have been fabricated at various fluorine doping concentrations by spray pyrolysis technique. The films exhibit polycrystalline nature with a preferential growth orientation along (1 1 0) diffraction plane as evident from x-ray diffraction studies. The optical transmittance of the F:SnO2 films has increased from 68 percent to 80 percent. Photoluminescence studies revealed that strong violet emission peak corresponds to 400 nm and relatively weak red emission peak at about 675 nm was observed for all the F:SnO2 films. Increase in the\b{eta}eff value upon fluorine incorporation supports the applicability of the deposited films in passive optical limiting applications. The principal origin of second harmonic generation signals (SHG) for this type of nanostructures is played by the space charge density acentricity due to the F doping. The enhanced second and third harmonic generation signals observed on F:SnO2 nanostructures endorses the credibility of these materials in various nonlinear optical trigger device applications.

physics.app-ph↗